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UBUNTU-CVE-2025-3909 (CVE-2025-3909)

Vulnerability from osv_ubuntu – Published: 2025-05-14 17:15 – Updated: 2026-09-16 11:25 – Source website
VLAI
Details

Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.

Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "thunderbird",
            "binary_version": "1:128.12.0+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "thunderbird-gnome-support",
            "binary_version": "1:128.12.0+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "thunderbird-mozsymbols",
            "binary_version": "1:128.12.0+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "xul-ext-calendar-timezones",
            "binary_version": "1:128.12.0+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "xul-ext-gdata-provider",
            "binary_version": "1:128.12.0+build1-0ubuntu0.22.04.1"
          },
          {
            "binary_name": "xul-ext-lightning",
            "binary_version": "1:128.12.0+build1-0ubuntu0.22.04.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "thunderbird",
        "purl": "pkg:deb/ubuntu/thunderbird@1:128.12.0+build1-0ubuntu0.22.04.1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1:128.12.0+build1-0ubuntu0.22.04.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1:91.1.2+build1-0ubuntu1",
        "1:91.3.0+build2-0ubuntu1",
        "1:91.3.1+build1-0ubuntu1",
        "1:91.3.2+build1-0ubuntu1",
        "1:91.4.0+build1.1-0ubuntu1",
        "1:91.4.0+build2-0ubuntu1",
        "1:91.5.0+build1-0ubuntu1",
        "1:91.5.1+build1-0ubuntu1",
        "1:91.6.1+build1-0ubuntu1",
        "1:91.7.0+build1-0ubuntu1",
        "1:91.7.0+build2-0ubuntu1",
        "1:91.8.0+build2-0ubuntu1",
        "1:91.9.1+build1-0ubuntu0.22.04.1",
        "1:91.11.0+build2-0ubuntu0.22.04.1",
        "1:102.2.2+build1-0ubuntu0.22.04.1",
        "1:102.4.2+build2-0ubuntu0.22.04.1",
        "1:102.7.1+build2-0ubuntu0.22.04.1",
        "1:102.8.0+build2-0ubuntu0.22.04.1",
        "1:102.9.0+build1-0ubuntu0.22.04.1",
        "1:102.10.0+build2-0ubuntu0.22.04.1",
        "1:102.11.0+build1-0ubuntu0.22.04.1",
        "1:102.13.0+build1-0ubuntu0.22.04.1",
        "1:102.15.0+build1-0ubuntu0.22.04.1",
        "1:102.15.1+build1-0ubuntu0.22.04.1",
        "1:115.3.1+build1-0ubuntu0.22.04.2",
        "1:115.4.1+build1-0ubuntu0.22.04.1",
        "1:115.5.0+build1-0ubuntu0.22.04.1",
        "1:115.6.0+build2-0ubuntu0.22.04.1",
        "1:115.8.1+build1-0ubuntu0.22.04.1",
        "1:115.9.0+build1-0ubuntu0.22.04.1",
        "1:115.10.1+build1-0ubuntu0.22.04.1",
        "1:115.11.0+build2-0ubuntu0.22.04.1",
        "1:115.12.0+build3-0ubuntu0.22.04.1",
        "1:115.13.0+build5-0ubuntu0.22.04.1",
        "1:115.15.0+build1-0ubuntu0.22.04.1",
        "1:115.16.0+build2-0ubuntu0.22.04.1",
        "1:115.18.0+build1-0ubuntu0.22.04.1"
      ]
    }
  ],
  "aliases": [],
  "details": "Thunderbird\u0027s handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may incorrectly render it as HTML when opened, allowing the embedded JavaScript to run without requiring a file download. This behavior relies on Thunderbird auto-saving the attachment to /tmp and linking to it via the file:/// protocol, potentially enabling JavaScript execution as part of the HTML. This vulnerability was fixed in Thunderbird 128.10.1 and Thunderbird 138.0.1.",
  "id": "UBUNTU-CVE-2025-3909",
  "modified": "2026-09-16T11:25:27Z",
  "published": "2025-05-14T17:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-3909"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-3909"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/en-US/security/advisories/mfsa2025-34/#CVE-2025-3909"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1958376"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/security/advisories/mfsa2025-34/"
    },
    {
      "type": "REPORT",
      "url": "https://www.mozilla.org/security/advisories/mfsa2025-35/"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-7663-1"
    }
  ],
  "related": [
    "USN-7663-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-3909"
  ]
}



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